Stable, high strength, alpha titanium base alloys



United States Patent STABLE, HIGH STRENGTH, ALPHA BASE ALLOYS Robert I. Jalfee, Worthington, and Horace R. Ogden,

Columbus, Ohio, and MiltonB. Vordahl, Beaver, Pa.,-

No Drawing. Application March 8, 1957 Serial No. 644,713

'14 Claims. c1. 7s-11s.s'

This invention pertains to strong, ductile and thermally stable, alpha alloys of titanium, which are characterized by high strength and ductility at both room and elevated temperatures, and which retain these properties on'prolonged exposure to elevated temperatures in both stressed and unstressed conditions.

We have previously shown in Patents 2,669,513; 2,669,514; 2,703,278; and 2,779,677, that alpha titanium alloys containing aluminum, tin and antimony singly and in combination, have excellent strength and ductility properties over the ranges of about 0.5-8% aluminum, 1-23% tin and 1-18% antimony;

Our original investigations indicated that the aforesaid alloys containing any one orvmore of aluminum, tin and antimony within the ranges aforesaid, were all single phase, alpha alloys. Wehave now discovered that under certain conditions, an ordered or partially ordered arrangement of the titanium and alloy atomsis obtained in alloys containing one or more of these elements aluminum, tin and antimony in amounts above a certain critical upper limit. Our investigations indicate that this ordered st'ru'c-' ture results from the'formation of a Ti Al phase, a Ti Sn phase, a Ti sbphase, or if more than one'alpha stabilizer of this group is present, the aluminum, tin and antimony combine to form a Ti Al, Sn, Sb) phase. That is to say, when'any two or more of aluminum, tin andanti= mony are present in the alloy, the atoms of these" elements will appear indiscriminately and-in random sequence in the ordering, without aliecting the building up of the ordered structure. The composition of the completely ordered structure thus corresponds to Ti Al, Ti Sn, Ti Sb, if these elements are present individually, or to Ti (Al, Sn, Sb) if any two or more are present, and occurs at about 25 atomicpercent-of these alloying additions, or at about 16, 45 and 46 weight precent, for Al,"Sn and Sb, respectively.

The conditions under which this ordered phase starts to form are prolonged-exposure at elevated temperatures of about 8001000 F. Strain caused by stress appears to accelerate the formation of this ordering, particularly where the material is stressed at elevated temperatures on the order of 800-1000 F.

.For titanium-aluminum binary alloys, our investigations" have shown that this ordering becomes sufiiciently pronounced markedly to decrease ductility during aging, at:

around 6"to 8% by weight of aluminum, i.e., at about 67% aluminum if the aging is conducted at around 2,892,705 Patented June 30, 1959 ICC num content for purposes of computing the ordering tendency is equal to the sum of the aluminum content plus /3 times the tin content plus /3 times the antimony content, considered on a weight percent basis, Thus the ordering tendency will become pronounced if the equivalent aluminum content of the alloy, computed in this manner, is upwards of about 7%, where any one, two or all of the elements aluminum, tin and antimony are present in the alloy. Or expressed more exactly in terms of atomic precent, the ordering becomes pronounced at 800 F. if the total atomic percent of the aluminum, tin and antimony present in the alloy is upwards of about 10.5 atomic percent and at 1000 F. if the-total atomic percent of these elements is upwards of about 12.5 atomic percent.

The formation of this ordered structure causes a loss in ductility of these alloys. Although the alpha alloys of the above patents have, in the condition as annealed above the maximum temperature at which ordering occurs or as quenched to room temperature therefrom, excellent strength and ductility at room temperature, nevertheless if these alloys containing above the critical aluminum equivalent content aforesaid, are subjected to prolonged service at temperatures around 800l000 F., loss in ductility will occur. And since the strength of these alloys is dependent on the totalalloy content, the maximum strength of these Ti-(Al, Sn, Sb) alloys, suitable for use at temperatures of 800-1000 F. will be limited by the maximum or cniticalequivalent aluminum content aforesaid.

Now we have discovered, in accordance with one aspect of our present invention, that zirconium additions to alpha alloys containing one or more of aluminum, tin and antimony, will produce strengthening of these alloys Without promoting the formation of the ordered Ti (Al, Sn, Sb) type of phase, so long as the equivalent aluminum content is" less than 6% by weight or'less than 10.5 atomic percent of the alloy. Therefore, the maximum strength obtainable in a stable alpha alloy of this type will be greater for alloys containing zirconium than for those in which no zirconium is present. The zirconium added to such alpha alloys replaces part of the titanium in the Ti (Al, Sn, Sb) compound, which can thus be expressed as (Ti, Zr) (Al, Sn, Sb), and" does not alter significantly the critical equivalent aluminum content of 7 weight percent at which ordering becomes pronounced; Thus, for example, we

have found that a Ti4All2Sn alloy, the equivalent aluminum content of which as above computed, is 8.0% by weight, i's unsta'ble; while a Ti4A1-12Zr alloy having an equivalent aluminum content of 4% by weight is stable; and also that a Ti6Al6Zr alloy having an equivalent aluminum content of- 6% by weight is stable.

In our discussion thus far, we have confined attention to -the alpha promoters aluminum, tin and antimony which enter the ordered position X in the ordered phase Ti X, H and to'zirconium, which substitutes, as noted above, for

partof the titanium in the ordered phase and hence does not promote ordering. Additional alpha promoters which enter theordered position X when they dissolve in alpha titanium are silver and indium, which thus .up to the 800 F. and at about 78% aluminum if the aging is- Inthe case of titanium-tin and" Our investigations have further shown'that insofaras concerns their effects on thistendency'towardordening;

about 3% by weight of tin or antimony is equivalent-to about 1% by weight of aluminum. Thus, where, two or" all of'these'elements are present, the equivalentalumi- "and 'Ti ln. about 3% by weight, and silver up to about 10% by limits of their solubilities in alpha titanium, are suscepti- 'ble to-the formation of ordered phases of the type Ti Ag, Indium is soluble in alpha titanium up to weight. Within these limits of alpha solubility, additions of these elements will therefore increase the strength of alpha titanium alloys, but if ordering embrittlement is to he'avoided, silver and indiumlike aluminum, tin and antimony, must-not be present in thealloy in total amount of more-than about-10.5 atomic percent.

Additional elements which, like zirconium, do not enter the ordered position X in the Ti X lattice, and therefore do not contribute to ordering, but which at the same time, produce strengthening of alpha titanium alloys, up to the limits of their alpha solubilities therein, are hafnium, and the various beta promoters such as vanadium, columbium, tantalum, molybdenum, manganese, iron, chromium, tungsten, cobalt, etc. Only a few of these beta promoters, however, have sufficient solubility in alpha titanium to impart material strengthening to alpha titanium alloys. -They are tantalum which is alpha soluble up to about by weight, columbium and vanadium which are alpha soluble up to about 3% by weight, and molybdenum and manganese which are alpha soluble up to about 0.5% by weight of each. The alpha solubilities of beta promoters like chromium, tungsten, iron, cobalt, nickel, copper and silicon are so low as not to permit of significant amounts of strengthening of alpha titanium alloys, but to the extent that these elements are soluble in alpha titanium, they will act like zirconium in that they will permit equivalent strengthening by substituting for part of the titanium and will not take up ordered positions in the lattice.

Since zirconium and hafnium are isomorphous with titahim, and produce only alpha alloys therewith at room or atmospheric temperature, they may accordingly be substituted for titanium in all proportions. A preferred range for zirconium as an alpha strengthener is, however, about 4 to Thus to summarize, the general formula for the completely ordered structure with reference to those of the elements above mentioned which have appreciable solubilities in alpha titanium is as follows:

(Ti, Zr, Hf, V, Cb, Ta, Mo, Mn) (Al, Sn, Sb, Ag, In)

All elements in the above formula must, as stated, be present only within the limits of alpha solubility for each or in total amount in the production of a'high strength, alpha alloys of titanium. Furthermore, if ordering embrittlement of the alloy due to aging at 8001000 F. is to be avoided, the total content of the elements which take up ordered positions in the Ti X lattice, namely, those which substitute for X therein, shall not exceed 10.5 atomic percent of the total alloy content, these being, as above stated, the elements aluminum, tin, antimony, silver and indium.

, Since the atomic weights of tin, antimony, silver and indium are close to one another, falling within the range of about 115-122 in round numbers, they will have approximately the same effect on the ordering tendency when alloyed with titanium, on an equal weight percent basis, i.e., percent-for-percent of each. And since as shown above, the equivalent aluminum content of tin and antimony on a weight percent basis is approximately Va times the weight percent of each present in the alloy, the same rule applies for silver and indium. Thus the general formula for the equivalent aluminum content on a weight percent basis is the sum of the aluminum content plus 6 times the total weight percent of tin, antimony, silver and indium present in the alloy. If the equivalent aluminum as thus computed is under 6%, the alloy is stable, and if over 7% the alloy is unstable. The critical limit of 6 weight percent of equivalent aluminum corresponds to the critical limit of 10.5 atomic percent of these elements present.

Since the alloying additions are usually given in terms of weight percent of each, the conversion to atomic percent for determining the ordering tendency is computed from the fraction in which the sum of the weight percent divided by the atomic weight of each of Al, Sn, Sb, Ag

' and In, appears in the numerator, while the sum of the weight percent divided by the atomic weight of each and every element present in the alloy appears in the denominator. If the fraction as thus computed is under 0.105, i.e., under 10.5 percent, the alloy is stable and if above this amount, the alloy is unstable.

As illustrative of the invention as thus described, reference will now be had to the test results in the following Table I, based on a series of alloy ingots produced by are melting titanium sponge of commercial purity except as perature tensile properties in the as annealed condition,

and also after aging exposure for at least 100 hours at 800 F. and 1000 F., in unstressed and/ or stressed condition as shown. The alloys were also tensile tested at 1000 F., with results as shown in the table.

TABLE I Tensile Properties, p.s.i. X M133, '1

Stress, Per- Min. Test 1,000 Percent Percent Composition, Percent (Balance Specimen Time, Temp., 1,000 cent Creep Temp., Elonga- Reduc- Titanium) Type Hrs. F. p.s.i. Plastic Rate F. tion in 1 tion in Strain per hr. 0.2% Ult. Area L T Ofiset Str.

Yield None 75 103 113 22 118 800 None 75 113 114 20 6A1-6Sn, RES-143545 (iodide Ber (T).-. 138 800 4. 82 0.00004 75 117 119 8 base). 120 1, 000 None 75 114 114 8 None 1, 000 58 66 30 None 75 116 119 10 118 800 None 75 113 123 10 6A1-6Sn, RES-143546 (sponge Bar (T).-. 138 800 1. 34 0.0005 75 120 121 4 base). 120 1, 000 None 75 118 120 2 None 1, 000 62 72 36 None 75 128 129 4 118 800 None 75 126 4 6A16Sn0.15 Ox, RES-143547. Bar (T)--- 120 800 0.09 Nil 83 0 120 1, 000 None 75 125 0 None 1, 000 66 79 32 Bar (L)... None 75 124 1 Bar (T).-. None 75 125 1 e a-- 1 a a a a1 000 one 6A1 6Sn 0.30x,RIN 1016 R2. Bar None 75 87 1 (T) None 75 75 1 Bar (L)--. 100 1, 000 None 75 B9 0 Bar (T)... 100 1, 000 None 75 60 0 None 75 139 139 2 118 800 None-. 75 139 4 6A16Sn0.075N, RES-143548. Bar (T)-- 800 0. 34 0.0004 75 106 0 v 120 1, 000 None 75 95 0 None 1. 000 61 73 24 TAB1E I--Co ntinued iScale-updngot. V V i H e b 0.010 9f metal was removed from diameter of reduced section after creep exposure (or igina1 diameter 0.125).

: of metal was removefiirom diameter ofTeduced'sectionaitercreepexposure' (onginal'diameter 0.125).

.meaflure As shown by the test results in the foregoing table; 7

it will be seen that all analyses having equivalent alu mmum of 6 or under on a weight percent basis, showed excellent stability after creep exposure for approximately 100 hours at 80091 and 65,000 p.s.i., and at 1000 F. and 15,000 p.s.i. stress, such, for example, as the analyses containing equivalent aluminum of more than showed instability in varying degrees as a result-of .such agmg and creep exposure tests, such for example,"

'as"the"Ti6Al-6Sn analyses with and without other additions, as indicated, and the TiAl5Sn5Zr,"

Ti5Al'-5Snl0Zr and Ti4Al6Sn6Sb' analyses. .Referring to the stable alloys of the first group, the

. weight of equivalent aluminum.

Alpha soluble vanadium additions have the same stabilizing action. Thus a Ti-12Sn4Al alloy containing the 8% aluminum equivalent had in the as quenched condition from 1500 F., a tensile elongation of 4% and an area reduction of 3%, which values were reduced to zero on aging for 100 hours at 1000 F. In contrast, a Til2Sn--4Al-2V alloy had as quenched from Ti 5Al2.5Sn alloy retained excellent ductility of tensile elongation before and after all exposure tests, combined with a high tensile strength of 140,000-

160,000 p.s.i. The same is true of the Ti--4Al l2Zr i fitantalum additions impart a similar stabilizing action.

and Ti-6Al-6Zr alloys which maintained tensile elongations of 12-22% and 11-16% after exposure. Similarlyi the Ti4Al4Sn10Zr alloy maintained excel lent tensile elongation of 1224% before and after creep exposure with an ultimate strength of about l30,0 00 p.s.i.

The copper-bearing analyses containing equivalent aluminum under 6 were not quite so stable as those above; discussed, because copper reacts with the titanium to form the compound Ti Cu, which thus increases the per-f1 duction of 18%.

1500 F., a tensile elongation of 10% and an area re- On aging for 200 hours at 1000 F., the tensile elongation was found to be 10% and the area reduction 22%. Thus the alpha soluble addition of 2% vanadium to the Ti12Sn-4A1 base alloy transformed it from a highly unstable to a highly stable alloy. Other tests have shown that alpha soluble molybdenum and As to the interstitial additions, carbon, oxygen and nitrogen, it will be seen firom Table I that they have a generally detrimental elfect on stability, and hence are cipitate out during aging exposure and thus tends to reduce ductility. Copper, however, has a marked strength ening action on the alloy as shown by the ultimate strengths varying from about 140,000 to 160,000 p.s.i. for the Ti12Zr--3Cu and the Ti6Al6Zr3Cu alloys. These alloys also having excellent creep strength as 160,000 p.s.i. has quite good stability, with tensile elon---- gations maintained being about 1012% before and after creep exposure.

All rapidly eutectoid compound-forming elements, such as cobalt, nickel, silicon, beryllium, etc., have the same effect as copper, in that they react with and tie up some of the titanium, thereby to increase the atomic percentage of aluminum and equivalent atoms present in the alpha matrix.

The effect of the various interstitial and beta promoter additions within the limits of alpha-solubility, as shown in the table, is somewhat masked by the fact that these additions were made in each instance to the Ti6Al--6Sn base alloy containing equivalent aluminum of 8% and hence above the limit of 6 for stability, the base alloy itself being unstable for this reason as shown by the T i--6Al6Sn analyses containing no such additions. It will be seen, however, by comparison that alpha soluble not desirable additions to alpha alloys as adjudged from this standpoint, despite the increase in strength imparted thereby.

The alloys of the invention have good welding properties as shown by the test results in the following Table TABLE II Bend-test results for alpha alloys before and after welding [Annealed 4 hours at 1600 F. and air cooled] Minimum Bend Radius, '1, Longi- Alloy N 0. Composition, percent tudinal (Balance Titanium) Base Welded RES-1435-23 4Al4Sn10Zr 3.1 7.2 IPA-2212 5.2 5.3 6. 7 4. 0 3. 5 6.8 3.9 4. 0 2. 5 7. 4 3. 3 5. 8 4. 6 8. 0 3. 6 5. 3 4. 4 7. 6 2.6 2. 3 2. 6 3. 7 2. 3 6. 7 2. 9 5. 8 2.6 5.2 3.0 7.6 4A16S116Sb 3. 5 8.0

The room temperature mechanical properties of additional TiAlZr alloys according to the invention as annealed at 1600 F. are given in the following Table III; while the microstructures of these alloys as annealed at 1600 F. are given in the succeeding Table IV. This table also gives the -hour, 800 F. bend-creep and bend-creep-bend test results for this same group of alloys.

TABLE III Hardness, bend, and room-temperature longitudinal sheet tensile test results for TiAlZr alpha alloys [Annealed 7 hours at 1600 F. and air cooled to room temperature] Tensile Properties: Composition, p.s.i. 1,000 Percent Percent Alloy Number percent (Bal- Elongation Reduction VHN MBR, T

anco Titanium) 1n 1" in Area (Long) 0.2% Offset Ultimate Yield Strength 4Al-6Zr 39 94 15 37 310 3. 9 4A1-12Zr 106 112 13 24 347 4. 0 tAl-ISZr 108 114 6 10 387 4. 4 4Al24ZR 116 119 2 6 374/405 5. 7 4Al-6Zr 99 20 28 351 3. 7 5Al-12Zr 118 121 5 7 365 4. 7 5A1-l8Z1 127 129 3 6 405 2. 5/Br 5Al24Zr 132 133 1 5 396 Br 6A1-6Z1L 111 13 27 386 3. 9 6A1-12Zr 122 123 15 35 393 4. 2 6A1-18Zr 131 131 9 20 416 4. 2 6A1-24Zr 1 3 417/472 Br 1 [Annealed 7 hours at 1600 F. and air cooled to room temperature] Before Exposure IOO-Hr. 800 F. Exposure Composition, Alloy number percent (Balance Titanium) MBR, T Residual MBR, T

Structure VHN (Long.) Stress, VHN (Long.)

1,000 p.s.i.

PA-2240 4Al-6Zr Trace 13 310 3. 9 33 316 2. 2 IPA-2241. Trace B 347 4. 46 354 8. 8 114-2242. Approx. 5B 387 4. 4 52 358 Br PA-2243 Approx. 15B 374/405 5. 7 64 386 Br PA2244 Trace B... 351 3.7 49 346 3. 8 PA-2245. Trace B 365 4. 7 PA-2246 Approx..4B .405. 2.5/Br PA-2247. Approx. B 396 Br PA-2248. Trace B 386 3. 9 IPA-2249. .Trace B 393 4. 2 IPA-2250. Approx. 413 416 4. 2 64 396 B1 PA-2251 Approx. 10B 417/472 Br PA-2220 2 4Al6Zr30u O 335 5. 2 48 344 4. 9 Int-2230 4Al-6Zr6Cu 319 Br 50 332 9. 6 PA-2231 4Al12Zr30u ,0 330,, 4.7 54 341 4.4 PA-22l8 B 4All2Zr6Cu O 364 Br 56 363 Br 1 B =beta, O =comp0und. All the Ti,Al Zr compositions are predominantly equiaxed alpha structures having the beta phase intergranularly in the described amounts. The TiAlZr-Cu compositions have both equiaxed and acicular alpha in addition to the compound phase.

2 These data have been included to show the efiectsof a dispersoid addition on the Ti-- 4A1(6, 12) Zr base. The alloys have been annealed 24 hours at 1400 F., furnace cooled to 1100 F., held 16 hrs. at 1100 F., and air cooled to room temperature.

The beta stabilizing eifect of zirconium is demonstrated by the structures observed for this group of Ti--AlZr alpha alloys. The 1600 F. annealing temperature resulted in a two-phase structure. This varies from traces "of betaphasefm- 6v to 12% zirconium contents,;to

beta phase for 24% zirconium content, in a predominantly The alloys of the invention also have good oxidation resistance at temperatures up to about 1800 F. and reasonably good oxidation resistance at about 1900 F. as shown by the test results in 'Table V below. The data in the lower portion of this table on unalloyed titanium and on titanium-tin and titanium-tin-aluminum alloys is added for comparison.

TABLE V Oxidation test data for alpha alloys Composition, Percent (Balance Titanium) Weight Gain, mgJcui.

. 4Al4Snl0ZI, RE 8-1435-23 f Exposed in still air for 24 hrs. at 1,560 E. and air cooled to room temperature.

b Exposed in still c Specimens from air for 4 hrs. at 1,600 F. and air cooled to room temperature. above exposed an additional hrs. at 1,600" F. and air cooled to room temperature.

6 Exposed in still air for 4 hrs. at 1,800 F. and air cooled to room temperature. 6 Exposed-in stillair'for 4 hrs. at 1,920 F. and furnace cooled to room temperature.

{Alloy number.

leq ax da nh s ru u e- Th et s lo a at grain corners and intergranularly.

The foregoing data of Table jI also shows that elevetted-temperature strength as well as the room-tempera- {cure strength of the :TiAl.Zr alloys .is increased with increasing aluminum or zirconium content. Aluminum appearsto be about five or six times as potent as zirconium at room temperature on. a weightpercentage basis. .A decrease in ductility accompanies the increase iin strength. In the 800 F. bend-creep tests of Table 1H, the aluminum additions again appear to be about live or times as .efiective as. zirconium as an alpha 1. rengthening agent. 7 .T he bend-creep-bend'tests indicate at hemo ye lq ed qqmnos i s a m r t le duringthedOOhour, 800 F. exposure.

It will be noted from the above data that the addition of about 3% columbium imparts excellent oxidation resistance up to at least 1900 F.

The results ofshort time aging tests on additional alloys according to the invention, containing beta promoter additions Within the limits of their alpha solubilities-are shown in the following Table VI. The alloys thus tested were prepared by forging at 1800 F., followed by rolling at 1500 'F., to 0.08", then descaled, again rolled at 1400 F. to 0.045, held 15 minutes at 1400 F., furnacecooled therefrom to 1100 F., held one hour thereat, air cooled thence to room temperature and descaled before testing. In the table, the room temperature mechanical or tensile properties for the alloys are given for the as rolled and annealed condition, as prepared, supra, in-

cluding minimum bend values, and the minimum bend values are also given for some of the alloys after aging for 48 hours at 750 F.

TABLE VI Mechanical and aging properties of ternary Ti-Al-betaisomorphous alloys Tensile Properties: Min. Bend Rad. T Composition, p.s.i. X 1,000

Percent Percent; Percent (Balance Elongation Reduction VHN As Rolled and As Aged 48 Hrs. Titanium) in 1 in Area Annealed at 750 F.

0.2% Ofi- Ultimate set Yield Strength L T L T 89 103 12 40 283 88 97 20 51 309 2. 3 2. 8 2. 1 2. 9 65 79 19 41 300 O. 7 67 8O 18 45 276 0. 69 81 18 43 294 1. 1 85 93 23 a 51 306 2. 4 2. 4 1. 9 1. 9 89 98 52 317 2. 4 2. 0 1. 8 1. 9 75 86 22 46 287 1.2 1. 6 79 91 22 49 289 1. 5 1. 5 75 89 47 287 1.6 1. 5 81 88 9 28 317 1. 8 1. 8 93 102 19 38 354 1. 8 1. 8 93 102 22 47 342 1. 5 1. 5 93 106 12 31 363 3. 4 2. 7 82 94 20 321 0. 7 90 100 17 326 1. 5 101 116 12 291 2. 4 2. 3 2. 4 2. 4 96 106 19 51 319 2.9 5 7 2.5 2.8 121 127 15 44 325 2. 7 2. 7 4Al5Ta5V. 144 145 6 33 351 2. 8 3. 3

Iodide base titanium; balance titanium of commercial purity.

The lower effective limit for the elements having limited solubilities in alpha titanium such as indium, vana dium, columbium, molybdenum, manganese, etc., is about 0.1%, while for those elements having higher alpha solubilities, such as zirconium, hafnium, tantalum, silver, alu-.

minum, tin, antimony, etc., the lower effective limit is about O.250.5

Preferred alloys according to the invention are Ti(36)Al-(415)Zr Ti(3-6)Al-(4l0)Sn-(5l0)Zr wherein aluminum and tin are proportioned to provide equivalent aluminum of 6 or under.

The advantages of the present invention are not confined to alloys in accordance therewith having a sub-' stantially all-alpha structure, but also apply to such as have imparted thereto a mixed alpha-beta structure due to beta promoter additions in amounts exceeding their alpha solubilities as aforesaid. The effect of such addi tions is simply to reduce the volume of alpha present in a given total quantity of alloy. Discrete volumes of beta are found, and in these volumes all of the beta stabilizer content beyond that soluble in the alpha is concentrated, and the amount soluble in the alpha remains as described. Hence, obviously, the stability of the remaining alpha is subject to exactly the same conditions as described for the substantially 100% alpha alloy. The most stable of such mixed phase, alpha-beta alloys are those in which narily not contain more than about 15-18% of such beta promoters, as beyond this they tend to have a substantially all-beta or a mixed beta-eutectoid structure at normal temperatures. For these mixed phase alpha-beta .al-

lloys, chromium and manganese should not exceed about parison with alpha alloys according to the invention is shown in the following Table VII.

TABLE VII Composition, Percent Temp., Time, (Balance Titanium) F.

Weight hours Gain, mg.

Specimen Weight 8 Gain 6Al-4Mo msabamooowi mavmcocnwumm I:

What is claimed is: 1

1. A titanium base alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selectedfrom the group consisting of aluminum, tin, antimony, silver and indium, but not to exceed 7% of aluminum, 3% of indium and 10% of silver, and the maximum total content of the elements of said group being such that the percent of aluminum plus /3 times the percents of tin, antimony, silver and indium present, shall not exceed 7%, said alloy being characterized by high strength and ductility and by good stability on aging at 800-1000 C.

2. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony,

silver and indium, but not to exceed 7% of aluminum, 3% ofindium and 10% of silver, and the maximum total content of the elements of said group being such that the percent of aluminum-plus /3 times the sum of the percents of tin, antimony, silver and indium present,shall not exceed 7%, said alloy also containing up to 50% of metal of the group zirconium and hafnium, up to 0.5% of metal of the group molybdenum and manganese, up to 3% of metal of the group columbium and vanadium, up to 10% tantalum, and the balance substantially titanium, characterized by high strength and ductility and by high thermal stability.

3. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, but not to exceed 7% of aluminum, 3% of indium and 10% of silver, and the maximum total content of the elements of said group being such that the percent of aluminum plus /3 times the sum of the percents of tin, antimony, silver and indium present, shall not exceed 7 said alloy also containing about 0.25 to 50% of at least one element selected from the group consisting of zirconium, hafnium, columbium, vanadium, tantalum, molybdenum and manganese, but not to exceed 10% of tantalum, 3% of columbium and vanadium and 0.5% of molybdenum and manganese, balance substantially titanium, said alloy being characterized by high strength and ductility and by high thermal stability on aging exposure at 800-1000 F.

4. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin and antimony, but not to exceed 7% of aluminum, and the maximum total content of the elements of said group being such that the percent of aluminum present plus /3 times the sum of the percents of tin and antimony present, shall not exceed 7%, said alloy also containing about 4 to 12% of zirconium, balance substantially titanium, said alloy being characterized by high strength and ductility and by good stability on prolonged aging exposure at about 1000" F.

5. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin and antimony, but not to exceed 7% of aluminum, and the maximum total content of the elements of said group being such that the percent of aluminum present plus /3 times the sum of the percents of tin and antimony present, shall not exceed 7%, said alloy also containing about 4 to 12% of hafnium, balance substantially titanium, said alloy being characterized by high strength and ductility and by good stability on prolonged aging exposure at about 800- 1000 F.

6. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, but not to exceed 7% of aluminum, 3% of indium, and 10% of silver, and the maximum total content of the alpha promoters of said group being such that the percent of aluminum present plus /3 times the sum of the percents of tin, antimony, silver and indium present, shall not exceed 7%, said alloy also containing about 0.1 to 10% of at least one beta promoter selected from the group consisting of tantalum, columbium, vanadium, molybdenum and manganese, but not to exceed 0.5% of molybdenum and manganese, balance substantially titanium, said alloy having a substantially all-alpha microstructure and being characterized by high strength and ductility and by good stability on prolonged aging at 800-1000 F.

7. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, but not to exceed 7% of aluminum, 10% of silver and 3% of indium, and the maximum total content of the elements of said group present being such that the percent of aluminum present plus times the sum of the percents of tin, antimony, silver and indium present, shall not exceed 7%, said alloy also containing up to 50% of metal of the group zirconium and hafnium, up to 10% tantalum, up to 3% columbium, up to 0.5% of metal of the group molybdenum and manganese,balance substantially titanium, said alloy having a substantially all-alpha microstructure, and being characterized by a tensile elongation of at least 10% on prolonged aging ex posure at 800-1000 F.

8. An alloy consisting essentially of about: 0.5 to 23% by Weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, but not to exceed 3% of indium, 7% of aluminum and 10% of silver, and the maximum content of elements of said group present being such that the percent of aluminum present plus /3 times the sum of the percents of tin, antimony, silver and indium present shall not exceed 7%, said alloy being characterized by a substantially all-alpha microstructure and by a tensile elongation of at least 10% on prolonged aging exposure at 800-l000 F.

*9. An al'loy consisting essentially of about: 3 to 6% aluminum, 4 to 12% zirconium, balance substantially titanium, characterized by high strength and ductility and high thermal stability on aging at about 2300-1000 F.

10. An alloy consisting essentially of about: 3 to 6% aluminum, 4 to 10% tin, 5 to 12% zirconium and the balance substantially titanium, characterized by high strength and ductility and high thermal stability on aging at about 800-1000 F.

11. An alloy consisting essentially of about: 4 to 6% aluminum, 4 to 12% zirconium, 3 to 6% copper and the balance substantially titanium, characterized by high strength and ductility and high thermal stability on aging at about 800-1000 F.

12. An alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, but not to exceed 7% of aluminum, 3% of indium, 10% of silver, 20% of tin, and 18% of antimony, and the maximum total content of the elements of said group being such that the percent of aluminum plus /3 times the percents of tin, antimony, silver and indium present, shall not exceed 7 said alloy also containing about 0.5 to 18% of at least one beta promoter, balance substantially titanium, said alloy being characteried by high strength, ductility and thermal stability and by good oxidation resistance at elevated temperatures up to 1800 F.

13. A titanium base alloy consisting essentially of about: 0.5 to 23% by weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, the total content of the elements of said group present being such that the percent of aluminum plus /3 the total percent of tin, antimony, silver and indium present is at least 7%, said alloy also containing 0.5 to 3% of metal of the group columbium and vanadium for improving stability of said alloy on aging at about 800 to 1000 F.

14. A titanium base alloy consisting essentially of about: 0.5 to 23% by Weight of at least one alpha promoter selected from the group consisting of aluminum, tin, antimony, silver and indium, the total content of the elements of said group present being such that the percent of aluminum plus /3 the total percent of tin, antimony, silver and indium present is on the order of 6 to 10%, said alloy also containing 0.5 to 3% of metal of the group columbium and vanadium for improving stability of said alloy on aging at about 800-1000 F.

(References on following page) UNITED STATES PATENTS Jaffee et a1 May 13, 1952 Jafiee et a1 Feb. 16, 1954 Finlay Mar. 1, 1955 Jaffee et a1 July 10, 1956 Jaifee et a1 July 10, 1956 Vordahl Nov. 6, 1956 16 FOREIGN PATENTS France Feb. 24, 1954 France Dec. 8, 1954 France Dec. 8, 1954 Great Britain Sept. 19, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,892,705 June 30, 1959 Robert 1., Jaffee et al It is hereby certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 39, for "Ti Al" read Ti (Al columns 3 and 4., TABLE I, under the heading "Test Tempo Fa sixth line from the bottom, for "76" read 75 5 columns 5 and 6, same TABLE I, continued, under the needing "Composition, Percent (Balance Titanium), third composition from the bottom, for the ingot number "1335" read me 1435 same table under the heading "Temp. F." line '7, for "760" read 800 same table,

the heading "Min. Creep Rate per hr, second line from hottom, for ":LOQQ" read w 0.,0006 column 12, line '72, for "8OO-=1OOQ Go reed em 0 39"" w igned sealed this let day of December 3.959o

'5 ROBERT C. WATSON if Attesting Officer Commissioner of Patents 

1. A TITANIUM BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT: O.5 TO 23% BY WEIGHT OF AT LEAST ONE ALPHA PROMOTER SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, TIN ANTIMONY, SILVER AND INDIUM, BUT NOT TO EXCEED 7% OF ALUMINUM, 3% OF INDIUM AND 10% OF SILVER, AND THE MAXIMUM TOTAL CONTENT OF THE ELEMENTS OF SAID GROUP BEING SUCH THAT THE PERCENT OF ALUMINUM PLUS 1/3 TIMES THE PERCENTS OF TIN, ANTIMONY, SILVER AND INDIUM PRESENT, SHALL NOT EXCEED 7%, SAID ALLOY BEING CHARACTERIZED BY HIGH STRENGTH AND DUCTILITY AND BY GOOD STABILITY ON AGING AT 800-1000* C. 